Coaxial electrical connectors are used in a wide variety of applications for transmitting direct current, such as in charger sockets for such devices as cellular telephones or the like. Such coaxial connectors include a center terminal and at least one auxiliary terminal spaced transversely or radially of the center terminal. Distal ends of the center terminal and the auxiliary terminal respectively mate with the positive and negative electrodes of a mating element such as a female coaxial connecting device. Opposite ends of the terminals may be connected, as by soldering, to appropriate circuit traces on a printed circuit board for transmitting current. In these connector arrangements, the center terminal is a critical component of the connector.
The terminals of such connectors typically are stamped and formed of conductive sheet metal material. In order to reduce the contact resistance of the coaxial connector to improve the stability of the circuit, the mating end of the center terminal is formed or rolled into a cylindrical configuration, and the terminating end of the center terminal is appropriately stamped and formed into a configuration for mounting the terminal and terminating the terminal, such as to the printed circuit board. Processing the cylindrical mating end of the terminal requires multi-axis rolling and forming technology which is complex and may result in inconsistent quality of the terminal and the connector. In addition, it is difficult to fix the center terminal in the housing of the connector without unduly increasing the size of the housing or affecting the stability of current transmission.
In an attempt to solve these various problems, FIG. 1 shows a coaxial connector, generally designated 10, as disclosed in Chinese Patent No. 01280613. The connector includes an insulating housing, generally designated 12; a center terminal, generally designated 14; and a pair of auxiliary terminals, generally designated 16 and 18. The center terminal is inserted into a passage 12a of housing 12; auxiliary terminal 16 is inserted into a passage 12b in the housing; and auxiliary terminal 18 is inserted into a passage 12c in the housing. Center terminal 14 includes a hollow cylindrical mating portion 14a, a solder tail portion 14b and a right-angled connecting portion 14c joining the mating portion to the solder tail portion. A pair of mounting interference wings 14d project outwardly from opposite sides of the center terminal generally at the right-angled connecting portion 14c thereof. The mounting interference wings have outwardly projecting teeth 14e. 
Still referring to FIG. 1, when center terminal 14 is inserted into passage 12a in housing 12, the mounting interference wings 14d are inserted into a pair of slots 12d at opposite sides of passage 12a with an interference fit to hold the center terminal in the housing. However, since mounting wings 14d are plate-like members and their contact area with inner walls of the housing is rather small, the interference affect is rather small and it is difficult to ensure stable mounting of the center terminal. Unstable mounting will affect the stability of current transmission. The mounting interference wings cannot be made significantly larger to increase the holding affect on the center terminal without significantly increasing the size of housing 12 which would be undesirable.
FIG. 2 shows another coaxial cable, generally designated 20, according to the prior art. This connector includes an insulating housing, generally designated 22; a center terminal, generally designated 24; and a pair of auxiliary terminals, generally designated 26 and 28. The center terminal is inserted into a passage 22a in the housing, and the auxiliary terminals 26 and 28 are inserted into a pair of passages 22b and 22c, respectively, in the housing. Again, center terminal 24 has a cylindrical mating portion 24a, a solder tail portion 24b and a connecting portion 24c joining the cylindrical mating portion to the solder tail portion. The mating portion has a pair of resilient contact fingers 24d to enhance the contact engagement with a mating female connecting device. In order to improve the holding capabilities of center terminal 24 within housing 22, a pair of mounting interference hooks 24e are inclined outwardly from opposite sides of mating portion 24a near connecting portion 24c. Although hooks 24e (FIG. 2) might improve the stability of the center terminal versus wings 14d (FIG. 1), the improvement is rather small even when combined with any interference effect generated by connecting portion 24c with housing 22. In order to increase the holding force, either the size of connecting portion 24c or wing portions 24e must be significantly increased which, in turn, will undesirably increase the transverse dimensions of housing 22. This would be undesirable when miniaturization of coaxial cables is ever-increasing.
The present invention is directed to solving these various problems of increasing the holding forces and, particularly, the stability of a center terminal in coaxial electrical connectors.